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Category Archives: Tips and Tricks

Interfacing an external ADC chip to FPGA/CPLD

Posted on April 26, 2012 by R-B Leave a comment

Chris (from PyroElectro) has posted an article on interfacing an external ADC chip to FPGAs and CPLDs, which do not have A/D capabilities built-in. He illustrates the idea with an Altera EPM7128 and a MAX150 8-bit analog to digital converter IC. The test analog signal is derived using a potentiometer and the converted digital output is shown using an LED bargraph display. The interface between the CPLD and ADC has been implemented in VHDL.

Using CMOS camera for sensing applications

Posted on April 6, 2012 by R-B 3 comments

Ibrahim Kamal from IKALOGIC informed me about his latest article on the use of CMOS camera for sensing applications posted on his website. It’s true that interfacing a CMOS camera with 8-bit microcontrollers has not been very common. There’s a stereotype that much faster and powerful microcontrollers are required to process the output of a CMOS camera, which may not always be true, as illustrated by Ibrahim Kamam. In fact, it all depends on the type of application you choose with a CMOS camera. The article discusses about the possibility of using a CMOS camera for sensing applications by reducing

A brief overview of Allegro ACS712 current sensor (Part 2)

Posted on January 25, 2012 by R-B 37 comments

In the first part of this discussion, the features of ACS712 device were briefly discussed. Now we will use that theory to implement the ACS712 sensor to make a simple DC current meter. The analog output voltage from the sensor is measured through an ADC channel of the PIC16F1847 microcontroller. A voltage to current conversion equation will be derived and implemented in the firmware of the PIC microcontroller and the actual load current will be displayed on a character LCD.

A brief overview of Allegro ACS712 current sensor (Part 1)

Posted on January 25, 2012 by R-B 18 comments

Sensing and controlling current flow is a fundamental requirement in a wide variety of applications including, over-current protection circuits, battery chargers, switching mode power supplies, digital watt meters, programmable current sources, etc. One of the simplest techniques of sensing current is to place a small value resistance (also known as Shunt resistor) in between the load and the ground and measure the voltage drop across it, which in fact, is proportional to the current flowing through it. Whereas this technique is easy and straightforward to implement, it may not be very precise because the value of the shunt resistor slightly

Measurement of temperature and relative humidity using DHT11 sensor and PIC microcontroller

Posted on January 10, 2012 by R-B 140 comments

Measurement and control of temperature and relative humidity finds applications in numerous areas. These days devices are available which have both temperature and humidity sensors with signal conditioning, ADC, calibration and communication interface all built inside them. The use of such smart sensors greatly simplify the design and reduces the overall cost. We discussed in past about Humidity and temperature measurements with Sensirion’s SHT1x/SHT7x sensors. These sensors are capable of measuring both temperature and relative humidity and provide fully calibrated digital outputs. While SHT1x/SHT7x are very accurate sensors, they are still expensive for hobbyists use. This articles discusses the DHT11 sensor

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